User talk:Gaaijz

From Rosetta Code


Welcome to Rosetta Code! If you have any questions, drop them in the appropriate talk page, and someone will get back to you. If you have a more general question, try Mwn3d's or my talk pages. --Short Circuit 04:10, 2 September 2008 (UTC)


Hey Arie. This is Dan Bron from the J forums. Tracy Harms is here too. It's good to have J representation on RosettaCode. I'm glad you posted a J solution to the Pyramid of Numbers, that was near the top of my to do list. Have you considered posting a task along the lines of your Rabbit Sequence?

Oh, by the way, I linkified your user page. I hope you don't mind. Go ahead and revert it if you like it better the other way.

DanBron 13:48, 2 September 2008 (UTC)


Two different approaches with Haskell for the zigzag task.

zigzag m n = take m .transp_wof $ zipWith id (cycle [reverse,id]) antiDiags where
  mmn        = min m n
  antiDiags  = unfoldr (\((c:cs),xs) -> if null xs then Nothing else Just (take c xs,(cs,drop c xs)))
               ([1..mmn-1]++(replicate (succ.abs $ m-n) mmn)++[mmn-1,mmn-2..0], [0..m*n-1])
  transp_wof = unfoldr (\xs -> if null xs then Nothing else Just $ next xs)
  next xs    =  (,) (concatMap (take 1) ks) ((map (drop 1) $ drop 1 ks) ++ ts)
       where (ks,ts) = splitAt n xs

Slower version, almost complete emulation of the J-solution
groupon f x y= f x == f y
tab n = fst . until (null.snd) (\(xs,ys)-> (xs++[take n ys], drop n ys)) . (,) []
grade xs = map snd. sort $ zip xs [0..] 

zigzagJ m n = tab n. grade .concat $ zipWith id (cycle [reverse,id]) fdiag
  where fdiag = map (map snd). groupBy (groupon fst).sortBy (comparing fst)
                $ zip (map sum $ sequence [[0..m-1],[0..n-1]] ) [0..]
*Main> sum $ zigzag  500 500
(0.69 secs, 103908376 bytes) 

*Main> sum $ zigzagJ 500 500
(4.55 secs, 575802084 bytes)

Words Of Equal Characters

Hi, Could you add some sample output to your Haskell implementation? Thanks. --Paddy3118 18:47, 26 September 2008 (UTC)

Generic swap

Hello again. I've responded to your question re: Generic swap.

--DanBron 16:05, 29 September 2008 (UTC)

J alphabet gaps

Hey. I've responded to your inquiry about alphabetic gaps in J's task coverage on RC.

--DanBron 20:26, 23 January 2009 (UTC)

Miller Rabin: 946 prime?

Hi Gaaijz, I was doing the left truncatable prime task and started by improving the Miller Rabin primality test for Python after finding what turns out to be one of the references you cite on your Haskell version. On testing 901 to 1000 for primality in my Python I noticed that the Haskell version says 946 is prime on the page? I checked the page history and found that you had the 946 from the beginning - i.e. it is not a malicious edit so I thought I'd give you a chance to look into the Haskell code rather than me just removing the 946 from your output, which was my first thought. --Paddy3118 (talk) 05:36, 23 July 2013 (UTC)